Boy have I had, and had, and had, the argument about Natural Gas. When I got my present job I noticed we had about 80% (of 45 gensets) that were natural gas.

I then checked and we were not installing battery back up lights, so the gens were the back up.

I asked who had approved the use of natural gas since it was a violation. 700-12 states you will have a 90 minute supply on site, and natural gas cannot meet that requirement. I got no reply, but did notice they quit fighting me about diesel generators. [Linked Image]

We just went over part of this in this thread: https://www.electrical-contractor.net/ubb/Forum18/HTML/000062.html

In case you can't tell, I don't believe Nat. Gas should be used for emergency backup gens, but limited to NON (Optional) emergency standby use. Should some disaster occur such as earthquake, tornado, or act of terrorism, you will lose the gas pretty quick.